The present invention relates to a novel delamination apparatus and method, and more particularly to apparatus and a method for delaminating a composite sheet structure comprising a plurality of selectively releasable superposed sheets.
There are a great many prior art references disclosing apparatus and methods for separating layers of laminating film units, for instance, for the purpose of rendering a developed image visible. Such apparatus and methods are commonly used in connection with so called peel apart film units and may utilize a blade of some kind insertable between two predetermined layers or sheets of a film unit fixed to the periphery of a rotating drum. For example see U.S. Pat. No. 4,670,085.
In general, the prior art apparatus and methods may be characterized as providing a peeling action, for instance removal of one layer from another. Such apparatus and methods however would not be suited for providing delamination as understood in the context of the present invention. Delamination in the sense used herein, is to be understood as meaning a process of separating cover or support sheets from opposite surfaces of a vertically frangible layer each carrying different portions of the frangible layer with it as determined by the strength of an adhesive bond at any given point between the surfaces of the layer and the respective sheet. Vertical frangibility of the layer as used herein is intended to mean the ability of the layer to break in a direction normal to its surface by to exclude breaking of the layer between its surfaces.
A device and method for providing the delamination as set forth above is disclosed in U.S. patent application Ser. No. 07/616,796, filed Nov. 21, 1991, and has proved successful in achieving its various objectives.
In the copending U.S. patent application of F. S. Silveira and W. P. Tobin, Ser. No. 07/800,467, filed of even date, there is disclosed a further device and method for delaminating a composite sheet structure wherein the sheet structure is fed into the nip of upper and lower peel rollers and upon passage therethrough a strip sheet roller is rotated into position to bend and hold the laminate against the upper peel roller in a position to fracture a tab located on one sheet, from the other sheet, to initiate peeling. On reversal of the feed direction and passage of the laminate back through the nip of the strip sheet and upper peel rollers, the sheets of the laminate break away from one another. The separate sheets are then fed in different directions to either waste or for further processing.
It is a primary object of the present invention to provide improved apparatus and method of the type described for the controlled delamination and feeding of the laminate sheets during the delamination or peeling process.
It is another object of the present invention to provide an improved apparatus and method of the type described for delaminating a composite sheet structure which provides a significant improvement in the control of feeding of the delaminated sheets and tab breaking compared to the prior art.
A further object of the invention is to provide an improved apparatus and method for tab breaking and feeding the laminated sheets of a composite sheet structure comprising a plurality of selectively releasable superposed sheets which increases reliability of the delamination and feeding process.
And still a further object of the invention is to provide a novel delamination apparatus and method for the controlled delamination and feeding of the support sheets which makes possible a selective removal of portions of a frangible layer by sheets adhered to opposite surfaces of the layer.